1. Field of the Invention
One or more embodiments of the present invention relate to a secondary battery, in more detail, a secondary battery that makes it possible to electrically connect an electrode terminal or a cap plate with a plurality of electrode tab, using various types of welding.
2. Description of the Related Art
In general, various types of secondary batteries are used as power supplies that supply power to electronic devices and electric vehicles. A plurality of cells may be electrically connected in series or in parallel to supply necessary power, when those secondary batteries increase in size.
A jelly-roll, which is one cell, has a limited power that the jelly-roll can generate. Therefore, it is preferable to achieve desired capacity by connecting a plurality of cells in series or in parallel, rather than using one cell having large capacity, in order to implement large-sized secondary batteries. Accordingly, it is required to achieve necessary power by connecting a plurality of jelly-rolls and keep the charge amount of current.
It is difficult to smoothly operate the engine of electric vehicles with low power and it is impossible to operate the engine for a long period of time with a small charge amount. Therefore, it needs to achieve a necessary amount of power and current by organically connecting a plurality of jelly-roll.